I've got a shoal of 8 Harlequin Rasbora w/ a ratio of either 3/5 male:female or 4/4 male:female. I have noticed a lot of jousting among these fish and they will even chase members of the neon tetra shoal around. I got 8 because I thought the number would keep these guys chilled out. The HRs don't pay too much attention to the corydoras or Betta splendens however Paracheirodon innesi is a free target.

I know these are not cyprinids but even my Paracheirodon innesi /neon tetras, are a little territorial with-in their own species; something I find odd, because certain members of this shoal, do not like each other...... Tank 2 Big - 15 gallon Freshwater fish tank

Thank you for any advice. A link to the tank and specs is above. My Betta Splendens is like the most peaceful fish in the whole tank. Go figure?!

Neons are a nervous fish, and as such they tend to make themselves easy targets. How many neons do you have? Also are your neons smaller than your HRs? What kind of decor do you have in your tank? Typically shoaling fish become nippy if they feel over exposed or threatened (or when paired with slower tankmates) for the best luck keep the fish evenly grouped by species, and in groups of 6 or more, and of similar sizes and body types. So your 8 HRs should have 8 neons of an equal size. make sure you keep decor on all levels of the tank to encourage them to play and explore, rather than chase and nip each other.

Neons are a nervous fish, and as such they tend to make themselves easy targets. How many neons do you have? Also are your neons smaller than your HRs? What kind of decor do you have in your tank? Typically shoaling fish become nippy if they feel over exposed or threatened (or when paired with slower tankmates) for the best luck keep the fish evenly grouped by species, and in groups of 6 or more, and of similar sizes and body types. So your 8 HRs should have 8 neons of an equal size. make sure you keep decor on all levels of the tank to encourage them to play and explore, rather than chase and nip each other.

Most of the neons are approx 1 inch. The small neon are the aggressors typically and the same goes for the HRs. Both species have a shoal of 8. Most of the fauna and decor lye to the back of the aquarium. In time I plan on adding more to the foreground. I'd like to think there are adequate hiding spaces in the tank as is. The tank is pretty heavily planted as you can see from the profile posted.

The HR's have greatly calmed down. It have have just been the fish assigning pecking order as I added another 3 fish recently to the shoal. This morning the fish were schooling wonderfully; at least the HRs were. The neon generally school when I turn the tank light off.